I got a start on the tooling plate/hold down plate for the rotary table, something I've been wanting to make for quite a while but never took the day or so to do it. Started with a chunk of steel bar, 3.5 x 5 x 3/8" (largest I had that would not interfere with the column while spinning on the table), and laid out a grid of holes 1/2" apart across it. These holes will be threaded for the step-block hold-down clamps from the Sherline. There is also a couple rows of extra holes in between, once centered and one offset to one end. These will take a round button on the bottom to fit in the center hole of the rotary table, plus larger clearance holes to take some t-slot nuts to clamp it down to the table. There are a couple spots where these can go in, to allow offsetting the plate to one side and/or one end for doing different arcs. I'll show examples of that once it is all made.Anyway, here was the start, drilling the first side of the grid of holes on the mini-mill, which makes for a very nice drill press setup - would have taken lots longer to do this on the Sherline mill with all the cranking needed for the Z-axis.Then turned the plate around to do the other side - lined up with the first set of holes so the pattern is square.The extra rows of holes for the t-slot nuts and center boss show in the center a few rows to the right. I'd finish it up now, but the winter archery and pistol leagues have started up, so off to prep for that. Should finish the drilling tomorrow, then will take a bit to tap holes. And more holes. Then some more...

Not for long. After spending 30+ years making a living on computers, I much prefer the hands on manual controls! So, my version of cnc is Count Number Cranks!I am using the cnc adapters on the leadscrews, just because they have a better backlash setup than the incredibly stupid way Sherline depends on a tiny grubscrew into an aluminum shaft to use the handwheel itself for a thrust bearing.

Finishing up the fixture plate, almost ready to get back to the hinges on the bucket door. I still need to tap the rest of the holes in the plate, but will wait on that till I get the hinges done. So far I tapped enough to hold the hinges down, and wanted to see how it went together. Here is the bottom, with the centering button screwed into the center hole, and the t-nut bolts slipped through the outer holes.The button can be placed in the center, like shown, or in several spots off to the side in that row, as can the t-nuts. There is another row for them off to the right, for use in rounding off long parts like con-rods.Here is a view from the top, with one of the hinges held in place. I am using the hold-down set from the Sherline, but just threading the rods into the plate holes rather than into the usual t-nut slots.In the picture I show one of the smaller hold-downs and one of the larger ones with the step blocks, either will work with this setup. The bolt for the centering button only goes half way into the plate, so the center hole can be used both for centering the rotary table in the mill, as well as holding down parts. When profiling parts I'll put down some sacrificial material to lift it off the plate, like card stock or thin metal strips. This is a tool that I've wanted to make for years, finally got around to it! Another of those 8 year and a day projects... Could have bought one, but could not see paying the prices they want for a simple block full of holes!Anyhow, off to lunch, then back at the hinge plates!!

That's pretty neat, Chris.So how did you center the "J" on the RT? just eyeball it? Or did you do something to help get it more accurately located?Kim

For recessing the inside of the part with the recess parallel to the edge, I start out with an eyeball guess, and just finger-tighten the hold down clamps so it doesn't shift too easily, then run the mill cutter down to the existing outside edge, with the tip of the cutter just above the part. Crank the table in/out till the edge of the cutter is next to the edge of the part, then cranked the rotary table around, and watched where it wandered off - repositioned the part, did that a couple more times till the tip of the cutter followed the part nicely. Clamped down the part tight, one more check, then I moved the table over and started the real cut. The inside and outside curves on the J are not concentric, so I had to reposition the part for the other edge. After cutting each edge, I made some felt-tip marks tracing the curves on the holding table, to make the eyeball guess a lot closer when doing the opposite face and the second part. A little alcohol on a tissue takes the felt tip off again when done.

If I was doing something like a eccentric follower or a con-rod, I'd make a little disc with a bolt hole in the center, where the outside edge of the disc has a stepped lip that is a close fit to the hole in the part, then bolt that disc into the center hole of the table (same hole where the centering button is on the bottom of the table) - that would auto-center the part onto the table and the rotary table.

Great lead in to these photos - just finished recessing the first hinge plate. I started out with the inner curve of the J centered as described above, and milled a slot 0.050" deep around that arc.Then re--positioned to center the outside curve, and did that section too...I re-positioned the clamps to get the arm of the J clear, turned the rotary table till the cutter ran down parallel to the outside length of the arm and cut there, then turned the rotary table to parallel the inside of the arm, and finished up the cut:Repeated the whole process on the opposite face of the part, so the cross section of the part looks like an I beam, and have one part done, one part to go...The ends of the recess should continue out to a point where the sides of the arm come together, but the end mills I have don't go that small, so I'll finish that off with the little air-powered rotary too with a dental bit - will show that after it is done. The inside corners up at the pivot hole will get trimmed up too.

Thanks for the write-up, Chris. Seems like a reasonable method. Could you have done the outside curve at the same time as the inner part? so that you had a way to register the 'J' using a hole - maybe recess the sides and do the outer curve before cutting away the inner curve so that you still had material in there to support the rest of the part? Just thinking how I might do it....

Thanks for the write-up, Chris. Seems like a reasonable method. Could you have done the outside curve at the same time as the inner part? so that you had a way to register the 'J' using a hole - maybe recess the sides and do the outer curve before cutting away the inner curve so that you still had material in there to support the rest of the part? Just thinking how I might do it....

But your results are incredible, as always! Kim

I don't think so - the inner and outer curves have different center points, which make the shape such that the end at the pivot hole is narrower than the end where it meets the arm of the J.

Oh. Wait. Now I get where you are going. Have two holes in the inner area, each at the center of the two arcs, and use that with a centering pin on the table.Yup! That would work! Could do the cut on the inner face of the part to separate that section last. The way I cut the blanks out of the larger bar meant I could not do that, since I had nested the shapes in and the center point wound up in mid-air. But, if you left the metal blank wider there, that would work fine.

Yet another proof that there is many more ways than one to skin a wildebeast!